A senior FBI official was removed from the Russia election meddling probe for sending text messages critical of President Donald Trump, the Washington Post reported Saturday.

Peter Strzok, deputy head of counter-intelligence at the FBI, was a key player in special prosecutor Robert Mueller’s probe into possible collusion between the Trump campaign and Russian operatives trying to tilt the election in Trump’s favor, the Post said. It quoted people familiar with the issue.

Strzok also worked on the probe into Hillary Clinton’s use of a private email server while serving as secretary of state.

During the Clinton investigation, Strzok was having an affair with a senior FBI lawyer named Lisa Page, the Post said.

Strzok and his lover traded text messages during the Clinton probe and the campaign in which they expressed anti-Trump feelings and other remarks apparently in support of Clinton, the Post said.